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A241625
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Smallest number m such that the GCD of the x's that satisfy sigma(x)=m is n.
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6
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1, 3, 4, 7, 6, 6187272, 8, 15, 13, 196602, 8105688, 28, 14
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OFFSET
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1,2
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COMMENTS
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This sequence is a sequel to A240667.
First unknown terms occur for n=14 and n=15.
Other large known terms occur at these indices: a(16)=2031554, a(25)=1355816, a(31)=8880128, a(80)=11532, a(97)=5488.
Small terms occur and are easily found when n belongs to A211656.
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LINKS
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EXAMPLE
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a(2) = 3, because the only x such that sigma(x)=3 is 2.
a(6) = 6187272, because the x's that satisfy sigma(x)=6187272 are [2651676, 2855646] and their GCD is 6.
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PROG
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(PARI) lista() = {lim = 12000000; nn = 100; out = "a241625.txt"; v = vector(lim, i, sigma(i)); w = vector(lim); for (i=1, lim, vi = v[i]; if (vi <= lim, if (w[vi] == 0, w[vi] = i, w[vi] = concat(w[vi], i)); ); ); for (i=1, nn, got = 0; write1(out, i, " "); for (j=1, #w, wj = w[j]; if (gcd(wj) == i, got = 1; write(out, j); break; ); ); if (! got, write(out, ); ); ); }
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CROSSREFS
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KEYWORD
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nonn,more,nice
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AUTHOR
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STATUS
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approved
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